The object of the investigation is to find out the effects of the experimental renal medullary necrosis on the structure and function of the kidney. Renal Medullary Necrosis: Mode of Calcification in the Renal Medulla: Following the induction of renal medullary necrosis by administration of 2-bromoethylamine hydrobromide, dystrophic calcification readily developed in the injured site of the medulla. The calcification occurred in close association with the basement membranes of the tubules and capillaries. Vesicular bodies seen about the basement membrane and collagen fibers appear to serve as a nucleation site for calcium deposit. Morphologic Changes of the Renal Papillae Observed in the Autopsy Specimens: Significant numbers of the adult renal papillae of the autopsy specimens had variable degree of interstitial hyalinization and loss of tubules and capillaries, and had shown calcium deposit in the interstitium. In addition, ultrastructure of the enlarged adrenal glands which takes place after the injection of 2-bromoethylamine hydrobromide has been investigated.